A veteran Las Vegas cop apparently shot his ex-policewoman wife and their 5-year-old son in the head before he turned the gun on himself.

The Clark County Coroner's Office said Kathryn Michelle Walters, 46; and Maximilian Walters, 5; each died of a gunshot wound to the head in their Boulder City, Nev., home on Monday.

As police surrounded the home, Hans Walters, 52, an off-duty lieutenant with the Las Vegas Metropolitan Police Department, set fire to the house and then fatally shot himself, according to accounts from the coroner and the Henderson Police Department, which is leading the investigation.

Investigators are combing through Walters' background looking for clues as to what made the 20-year veteran of the police force snap.

His wife, who went by her middle name, Michelle, had been employed by the Las Vegas Metropolitan Police Department as a patrol officer from January 1991 until August 2004, according a police spokesman.

The events unfolded Monday morning when Hans Walters called 911 to say he had killed his wife and son, according to a news release from the Henderson Police Department.

Walters, who was not identified by officials until late Tuesday, said he was "going to set his house on fire and harm any officer that came to the home," the news release said.

When Boulder City police arrived, they saw Walters standing in the doorway of the house, appearing to hold a handgun, according to Henderson police.

Walters was uncooperative, police said, and went back into the house, at which point he took his own life.

SWAT officers were called to the scene and entered the home, where they found the three bodies.

The Boulder City and Henderson fire departments were called to the scene to battle the blaze.

"It's sad," a neighbor who lived across the street from the family told ABCNews.com, adding he "didn't really know them."

When Sheriff Douglas Gillespie of the Las Vegas Metropolitan Police confirmed the killings, fire and suicide on Monday in a brief news conference, he assured the families and friends of the victims, "We will stand by your side and move through this unspeakable grief and support you any way we can."